An inductive write head consists of top and bottom magnetic poles and multi-turn coils to drive the field. The coils are encapsulated in usually one or two insulation layers, which are conventionally made of cured photoresist. A write gap between the top and bottom magnetic poles is typically of dielectric material, and is usually deposited prior to the insulation layer. The seed layer for plating the second writer pole (P2) is deposited using PVD process, such as sputter deposition. By this approach, some portion of the seed layer is on the cured photoresist insulation. The P2 layer is then electroplated into photoresist patterns to form the top pole structure. Experimental results suggest that magnetic films such as seed layers, which are typically NiFe films with different Fe contents, or other types of high moment magnetic films such as FeXN (X=Al, Ta, Rh, etc), exhibit poor magnetic properties when sputter deposited onto cured photoresist. This can be attributed to the significant difference in thermal mechanical properties between photoresist and magnetic films, as well as poor grain growth of the magnetic films on photoresist surface.
Also seed removal of the thick sputtered film requires a great amount of over milling into the insulation stack. The photoresist material has a relatively high milling rate and tends to become conductive at the milled surface. Therefore, the integrity of the insulation can be compromised during this process, and the coil may be damaged.
Thus there is a need for a new fabrication layer which can improve adhesion of magnetic films to the insulation layer, improve grain growth of pole seed layers, decrease the differential in thermal mechanical properties between the insulation layer and magnetic film layers, protect the coil from damage during ion milling processes, and preserve the desirable magnetic anisotropy properties of high moment magnetic films during fabrication.